Q: Do you intend to have all 280% flying mounts scale to 310% when a 310% mount is earned, or will only purchased mounts do so?
A: Our current plan, is that in Cataclysm, you can learn a new rank of flying that lets all flying mounts move at 310% (even current 280% mounts). That will probably be as fast as mounts will ever get. We don't like it that when you get a 310% mount that you stop using your old ones.

Q: If 310% speed is becoming trainable, does that mean we'll be able to fly in Azeroth from the get-go?
A: We have considered the concept of "Old Weather Flying." Just kidding. More than likely, you'll just be able to fly from the beginning.

No word yet on if players with current 310% speed mounts will still have to learn this new rank of flying skill or not. Previously, 310% speed mounts were seen as status symbols and prizes to be gained via achievements, PvP, rare drops or so on. Personally, I'm hoping people with 310% speed mounts are at least grandfathered in as it would be annoying otherwise to not even be able to ride your mount once the change went live.

On the up side, at least we'll be able to fly in Azeroth right away instead of having to train yet another rank of flying.